A security clearance can take anywhere from a couple months to more than a year depending on the particular circumstances candidates should be aware that the clearance process may take longer to complete if they, lived, worked, or were educated in a variety of locations, as this increases the number of places where references and records must be checked.  Any potential security concerns as listed in SEAD 4 (linked above) may also take longer to mitigate, depending on the complexity.  For more information, visit https://www.state.gov/security-clearances.